The search component was breaking down bootstrap dropdown menus. I traced the source of the problem, and figured one solution, BUT I don;t know how to do a pull request. So here I document problem and solution. Please consider as potential solution.

PROBLEM:

When loading a search component menu item, javascript console generated an error. This image the illustrates error in console:

In the file that triggers the error, chosen.jquery.js I found code which is implemented as PHP. This is the problem.

excerpt from file chosen.jquery.js lines 161 through 172 of the latest downloadable Joomla CMS package:

else {
this.default_text = this.options.placeholder_text_single || this.options.placeholder_text || Joomla.JText.('JGLOBAL_SELECT_AN_OPTION');
}
if (this.allow_custom_value) {
this.custom_group_text = this.form_field.getAttribute("data-custom_group_text") || this.options.custom_group_text || "Custom Value";
results_none_found_default = "Add custom value";
} else {
results_none_found_default = "No results match";
}
return this.results_none_found = this.form_field.getAttribute("data-no_results_text") || this.options.no_results_text || Joomla.JText.('JGLOBAL_SELECT_NO_RESULTS_MATCH');
};

Lines 161 and 171 call object Joomla.JText properties as if a PHP function was called method '_'.

SOLUTION

I solved this problem by modifying these two lines as follows:

this.default_text = this.options.placeholder_text_single || this.options.placeholder_text || Joomla.JText._('JGLOBAL_SELECT_AN_OPTION');

TO:

this.default_text = this.options.placeholder_text_single || this.options.placeholder_text || Joomla.JText['JGLOBAL_SELECT_AN_OPTION'];

AND

this.default_text = this.options.placeholder_text_single || this.options.placeholder_text || Joomla.JText._('JGLOBAL_SELECT_AN_OPTION');

TO:

this.default_text = this.options.placeholder_text_single || this.options.placeholder_text || Joomla.JText['JGLOBAL_SELECT_AN_OPTION'];

The solution calls the properties of the Joomla.JText object via the square brackets rather than the dot underscore etc...

Now, while in a search component menu item type, my Bootstrap dropdown menus work like a charm... (yes, I am a marketeer lol)